Gastroscopy technology has been widely used in clinical practice with good safety. Generally, a gastroscopy is not harmful, but general complications such as laryngeal edema and jaw dislocation, as well as serious complications such as reaction to anesthesia, gastric hemorrhage, gastric perforation, gastric mucous membrane damage, and cardiac arrest, may occur. 1. Laryngeal edema and jaw dislocation: during gastroscopy, due to the stimulation of gastroscope instruments and prolonged opening of the mouth, complications such as laryngeal edema and jaw dislocation may occur. 2. Reaction to anesthetics: before performing gastroscopy, patients will apply anesthetics, such as lidocaine, etc. If the patients are too sensitive and allergic to anesthetics, they are prone to adverse reactions and allergic reactions to anesthetics. 3. Gastric perforation, gastric hemorrhage: gastroscopy is mainly through the oral cavity, the gastroscope probe is placed into the stomach through the esophagus, when the operation is not appropriate or the probe is not used with proper force, it will stimulate the gastric mucosa, resulting in gastric wall perforation, hemorrhage and other serious complications. 4. Gastric mucosa damage: when patients undergo gastroscopy, when nausea, vomiting reaction is too heavy, and when the strength of the gastroscope is used unevenly, it will lead to ulceration, tearing and other damages to the gastric mucosa of the patients. 5. Cardiac arrest: in general, before gastroscopy, patients should do electrocardiogram and other tests to assess the cardiac function, when the patient’s physical condition is poor, cardiac arrest and other serious complications may occur, and should be rescued in time to avoid life-threatening injuries. Generally speaking, gastroscopy is a common operative examination, which is not harmful, but we should be alert to the occurrence of adverse reactions.